St. Louis, Missouri – Temperatures will climb into the upper 80s by Thursday afternoon, pushing near 90°F and bringing a summerlike stretch of heat across Missouri and Illinois ahead of a late-period shift toward storms.
According to the National Weather Service and NOAA’s Climate Prediction Center, both states are in a 70 to 80 percent probability zone for above-normal temperatures from April 16 through April 20. A broad heat dome over the central U.S. will limit rainfall early, allowing temperatures to steadily rise through the end of the workweek.
In the St. Louis metro area, including St. Louis County, St. Charles County, and Madison County in Illinois, highs are expected to reach 87 to 91°F between 2 p.m. and 6 p.m., with overnight lows holding in the mid to upper 60s. Along the I-55 and I-70 corridors, dry air and increasing southwest winds will accelerate vegetation drying, raising wildfire risk in open and rural areas.
Springfield, Missouri and central Illinois cities like Springfield and Decatur will see highs in the upper 80s, while southern Illinois communities south of I-64 may briefly touch 90°F during peak heating. Chicago will remain slightly cooler but still above normal, with highs in the low to mid-80s.
The precipitation outlook shows a transition during this period, with near-normal to slightly below-normal rainfall early shifting to a 40 to 50 percent chance of above-normal precipitation between April 18 and April 22. A corridor of heavier rainfall may develop from central Missouri into central and southern Illinois.
Residents should avoid outdoor burning, stay hydrated, and secure loose outdoor items as winds increase. Drivers should be alert for crosswinds on major interstates, especially I-55, I-57, and I-70.
The most consistent heat is expected through April 19, followed by increasing storm chances into early next week. Additional advisories are likely as this pattern shifts from dry heat to a more active storm setup.
